Improvement in screws



F. WQBROOK'S.

Improvement in Screws.

No. 131,843. Patented Oct. 1, 1872.

Whnesses Inventor.

PATEN OEEIoE.

FRANKLIN w. BROOKS, on NEW YORK, N. Y.

IMPROVEMENT IN SCREWS Specification forming part of Letters Patent No. 131,843, dated October 1, 1872.

To an whom it may concern:

Be it known that I, FRANKLIN W. BROOKS,

of the city, county, and State of New York,

have invented an Improvement in Screws, of which the following is a specification:

N atnre and Objects of the Invention.

This invention relates to permanent fastenings, or to that class of fastenings which are so constructed as, when once applied, to be in capable of removal or withdrawal without breaking or marring the same, so that the act may be detected if done by an unauthorized.

person. i

The invention consists in a screw for wood or metal, constructed with a head presenting square shoulders for the impact of the driver in sinking the same, and inclines to reject or cast off the driver if applied with endeavor to unscrew it. The construction facilitates the application of the tool to drive the screw, and

renders its-withdrawal by the same means impossible. Numbers or private marks may be applied to the screws to prevent their duplication or replacement.

Description of the Drawing. i

Figurel is a plan view of a countersunk wood-screw illustrating the invention. Figs.

2 and'3 are elevations of the same from the sides, indicated by the arrows at and b, respectively. Figs. 4, 5, and 6 represent a roundhead screw illustrating the invention. Fig. 4

is a plan of the same 5 and Figs. 5 and 6, elevations from the sides, indicated by the arrows c and d. i

Genemi Description;

approved general outline.

of the head 3 is formed with a pair of square inal manufacture. The screw may. have a threaded stem or bit, 2, of any approved construction, adapted for the material in which the screw is to be used, and a head, y, of any The upper surface shoulders, I 1, at the opposite ends and on opposit-e sides of a transverse line, and with a space, 2,between their faces of sufficient width to accommodate the point of an ordinary screwdriver. Opposed to these shoulders 1 are inclines 3, extending up from the base of one shoulder to the top of the other. The screwdriver need simply be applied across the low center of the head. On turning the same in the proper direction to sink the screw, the

shoulders l are engaged and furnish astrong hold. If turned in the opposite direction the driver slips over the inclines 3 and produces no other effect than the marring of the head. To withdraw the screw it is necessary to break off the head, or to cut or crush it in order to obtain a hold. The operation is thus rendered difficult or impossible of accomplishment by an unauthorized person without detection. The duplication or replacement of the screws may be prevented by the use of numbers or private marks stamped or impressed thereon.

The following is claimed asnew:

A fastening-screw constructed with a head, 3 having shoulders I for the impact of the driver in sinking the same, and opposing inclines 3 to reject the driver, so that the screw may not be withdrawn thereby, substantially as herein shown and described. I

To the foregoing specification of my improve ment in screws I have hereunto set my hand this 26th day of August, 1872.

FRANKLIN w. BEooKs.

Witnesses: M

OoTAvTUs KNIGHT, WALTER ALLEN. 

